The objectives of this application are to quantify the lubrication effects of human salivary macromolecules at the enamel interface and to identify the biological advantages of such lubrication. The proposal will seek to test materials of supersalivary performance as part of the overall goal of the parent RCOB proposal to enhance or improve upon nature. The specific aims are: (1) The development of an enamel substrate to provide baseline studies from which all other effects can be measured. The aim here is also to identify the biological consequences of the absence of a salivary pellicle in respect to such tribological properties as friction, wear and wear mechanism. (2) The second aim will be to construct a clear picture of the tribological properties of selected salivary macromolecules, previously demonstrated to exhibit lubrication activity. This will involve studies on human salivary glycoproteins including the proline rich glycoprotein and high and low molecular weight salivary mucins. In addition, we will chemically modify those molecules to ascertain the structural domain involved in lubricity. Such derivatives will be deglycosylated, deacylated or reduced and allcylated. The potential enhancement of lubrication by heterotypic complexing between human serum albumin and individual glycoproteins (plus their derivatives) will be explored. Finally, bi- and tri-composite salivary molecules (neoglycoproteins developed in subproject I.A.) will be tested. The methodology to achieve these objectives is based on servohydraulics configured as an artificial oral environment. Stimulated studies on natural teeth will be performed under complete environmental control. Frictional forces and wear mechanisms will be determined under different conditions. Special emphasis is laid on the integration of the proposal with the biochemical study of the overall RCOB proposal at SUNY at Buffalo. It is anticipated that such an integrated approach to the basic study of saliva would indicate synthetic routes to salivary materials of enhanced and prolonged lubrication effects, an essential requirement for the clinical management of salivary dysfunction and occlusal abrasion.